Notes

• Network Topologies
  • Bus
    • Devices are connected via a single cable
    • Simple and cost effective, but insecure and may have performance issues
  • Ring
    • Devices are connected on a loop where data travels one direction
    • Simple, but not scalable
    • Reduced data collisions, but still prone to performance issues
  • Star
    • Devices all connect to a central hub
    • Scalable, simple troubleshooting
    • Central device is a point of failure
  • Mesh
    • Devices each connect to multiple other devices, creating a web or “mesh”
    • Expensive + complex setup, not scalable
    • Very reliable, fault tolerant, good bandwidth
• A hybrid star / mesh topology is most common today
• Network Devices
  • Servers: provide resources, data, programs, or services to other devices
  • Hubs: a simple network device that sends incoming data to all attached devices
  • Switches: connects multiple devices and direct packets to their destination device
  • Routers: connect networks to each other and direct packets to their destination network
  • Bridges: connect network segments to make them act as a singular network
  • Access Points: allow wireless devices to connect to a wired network
• Types of Networks
  • Networks are categorized based on geographic range, number of devices, and how they connect
  • LAN (Local Area Network): covers a small area such as a home or school
  • WLAN (Wireless Local Area Network): LAN that uses WiFi instead of cables
  • WAN (Wide Area Network): covers large geographical areas such as cities or countries, connecting multiple LANs
  • MAN (Metropolitan Area Network): covers a city or small campus (in-between LAN and WAN)
  • PAN (Personal Area Network): a very small network consisting of connections between one person’s devices
• Network Addressing
  • IP Address
    • Parts of an IP Address
      • Network ID
        • Beginning of address
        • Anywhere from 8 to 30 bits
      • Host ID
        • Whatever is left over from Net ID
      • Subnet Mask:
        • Defines how many bits are in the Net ID
    • IP Address Example
      • Binary IP address:
        • 10000001101010100001001011011100
      • Translated to dotted decimal:
        • 129.170.18.220
      • Subnet Mask is /24
        • First 24 bits are Network ID
      • Net ID: 129.170.18
      • Host ID: 220
  • MAC Address
    • Unique to every network adapter
• Domain Name System (DNS)
  • A hierarchical, distributed system that translates website names into IP addresses, like a phonebook for the internet.
  • Example:
    • my.champlain.edu is 216.93.150.217
    • google.com is 8.8.8.8
• Open Systems Interconnection (OSI) Model
  • Network protocol framework that uses 7 layers
  • The layers define the different stages that data goes through to travel from one device to another over a network
  • OSI Model Layers:
    1. Physical Layer (1)
       • Wires and signals
       • carries data
    2. Data Link Layer (2)
       • Getting data across the wires
       • MAC addresses
    3. Network Layer (3)
       • Finding the best route
       • IP addresses and routers
    4. Transport Layer (4)
       • Keeping data in order
       • TCP and UDP
    5. Session Layer (5)
       • Managing connections
       • Keeping you connected
    6. Presentation Layer (6)
       • Translation Data
       • convert data into a format your device understands
    7. Application Layer (7)
       • What you see and use
• Network Security Toolkit: Wireshark
  • A popular tool for “capturing” network traffic. (also called sniffing
  • Captures all traffic to and from local host
  • Will parse packet “headers” and display the info in an organized way
  • Can filter results to show specific sessions, protocols, hosts, etc.

Vocabulary & Key Terms

Network

• A network is a group of interconnected devices that communicate and exchange data.
• Networks can have different topologies, devices, and sizes/types.

Slides

Mod 9 - Networking Basics (slides)